1. Field of the Invention
The present invention relates to a vibratory roller unit having a rotating shaft in a drum with a fixed inboard eccentric weight and an outboard eccentric weight rotatable with respect to the fixed inboard eccentric weight for varying the amplitude of the vibrations on the drum. Vibratory roller units are used to convert a powered lawn mower into a greensroller.
2. Brief Description of the Prior Art
Vibratory roller units of the kind described in U.S. Pat. No. 5,261,213 to Humphrey are used to convert a powered lawn mower of the type particularly adapted for mowing greens on golf courses into a greensroller by removing the reel cutting units and replacing them with vibratory roller units. The vibratory roller units are powered by the hydraulic motors which are used to power the reel cutting units.
With an unbalanced shaft, it is known that the amplitude of the vibrations is dependent upon the rotation rate of the eccentric weight but the speed of the hydraulic motors attached to the vibratory roller units are affected by the condition of the lawn mower, e.g., new or old, as the motors are powered by the lawn mower's hydraulic system. Thus, the same vibratory roller units on one lawn mower may apply different vibratory force on another mower.
In addition, the speed of the hydraulic motors may vary at the same hydraulic pressure from motor to motor and even with the same motor over time. Hence with a triplex mower, for example, with three different reel cutting units each powered by a hydraulic motor, the vibratory roller units may apply different vibratory forces because of the variation in the speed of the hydraulic motors. In some instances, it may be desirable to equalize the force applied by the different vibratory roller units in the greensroller.
And there are other variables. For example, it may be desirable to vary the vibratory force applied to the greens to achieve consistent ball roll distance between greens, some greens being firmer before rolling than others. Also more vibratory energy may be desirable during grow-in of new greens to settle the sand and/or soil based green or to disperse a sand topdressing when the grass is damp. More or less energy may also be desirable depending on the height of the cut and variety of the turf. Heretofore, variation in the vibratory force applied by a vibratory roller unit attached to a given lawn mower could be achieved by changing the ground speed of the mower thereby applying more or less vibratory force or by changing engine speed (RPMs) which affects the hydraulic pressure in the hydraulic system such that the hydraulic motors run faster or slower. These variations, however, are dependent on the skill of the operator and do not equalize the force applied by different motors.
Thus there is a need for a mechanism for varying the amplitude of the vibrations in a vibratory roller unit for use in a greensroller other than by varying the ground speed of the mower or by changing engine speed, preferably in a reproducible stepped manner that is less dependent on the operator. The present invention addresses this need.